Claudiosaurus ( claudus is Latin for 'lameness' and saurus means 'lizard') is an extinct genus of diapsid from the Late Permian Sakamena Formation of the Morondava Basin, Madagascar. It has been suggested to be semi-aquatic.
History and discovery
Claudiosaurus is known from the Sakamena Formation of Madagascar.
Claudiosaurus is found from the
Late Permian. Although a paper mentions that they have been also found in
Early Triassic deposits of Madagascar,
citation does not mention that
Claudiosaurus is from Triassic.
Description
Individuals of
Claudiosaurus reached a body length of approximately .
The body form of
Claudiosaurus is generally similar to those of other basal diapsids, although the neck of
Claudiosaurus is somewhat elongated, with 8 cervical vertebrae, and had a proportionally small head. The body has 16 trunk vertebrae with
gastralia present on the underside, and the tail has at least 45 caudal vertebrae. The jaws had numerous small teeth, with the roof of the mouth (palate) being covered in numerous denticles.
The
sternum is unossified.
The
pectoral girdle is similar to those of other primitive diapsids.
The
phalanges of the hands show a reduction of length away from the base, with the exception of the
phalange of the third digit, which is longer than the preceding phalange. The terminal phalanges are flattened.
The bones of
Claudiosaurus show
pachyostosis, suggested to possibly be an adaptation for aquatic life.
Ecology
Claudiosaurus is generally assumed to have been an amphibious animal, using its limbs for propulsion, though it was still likely capable of walking on land, and the skeleton shows only limited adaptations to aquatic life. It has been suggested to have fed on small invertebrates, such as crustaceans.
Classification
Upon its original description, Robert L. Carroll suggested that
Claudiosaurus belonged to
Sauropterygia (which includes
).
Other later studies have generally recovered it as a basal
Neodiapsida, sometimes as a member of the
Younginiformes.
was recovered as a relative of turtles by Li
et al. (2018), forming a clade with the basal neodiapsid
Acerosodontosaurus.
Although another study in 2020 specifically disputed these conclusions.
Paleoenvironment
The Lower Sakamena Formation was deposited in a wetland environment situated within a North-South orientated
rift valley, perhaps similar to
Lake Tanganyika. The climate at the time of deposition was temperate, warm, and humid, with seasonal rainfall and possible monsoons.
Flora from the formation includes the
Equisetales Schizoneura, the
Glossopteridales gymnosperm
Glossopteris, and seed fern
Lepidopteris. Other vertebrates known from the Lower Sakamena Formation include the
palaeoniscoid fish
Atherstonia, the
Procolophonidae parareptile
Barasaurus, the gliding
Weigeltisauridae reptile
Coelurosauravus, the neodiapsids
Hovasaurus, Thadeosaurus, and
Acerosodontosaurus, fragments of
Rhinesuchidae temnospondyls, an indeterminate
Theriodontia therapsid and the
dicynodont Oudenodon.
Further reading
